local n = io.read("*n")
local edge = {}
local parent = {}
local asked = {}
for i = 1, n do
  edge[i] = {}
  parent[i] = 0
  asked[i] = false
end
local ea, eb = {}, {}
for i = 1, n do
  local a, b = io.read("*n", "*n")
  ea[i], eb[i] = a, b
  table.insert(edge[a], i)
  table.insert(edge[b], i)
end
local ret = {}
asked[1] = true
local tasks = {1}
local ti, tj = false, false
for i = 1, n do
  local src = tasks[i]
  local f = false
  for j = 1, #edge[src] do
    local e = edge[src][j]
    local dst = ea[e] == src and eb[e] or ea[e]
    if e ~= parent[src] then
      if asked[dst] then
        ti, tj = src, dst
        f = true
        ret[1] = e
        break
      else
        asked[dst] = true
        parent[dst] = e
        table.insert(tasks, dst)
      end
    end
  end
  if f then break end
end

local m1, m2 = {}, {}
while 1 < ti do
  local pedge = parent[ti]
  m1[pedge] = true
  local p = ea[pedge] == ti and eb[pedge] or ea[pedge]
  ti = p
end
while 1 < tj do
  local pedge = parent[tj]
  m2[pedge] = true
  local p = ea[pedge] == tj and eb[pedge] or ea[pedge]
  tj = p
end
for k, _v in pairs(m1) do
  if not m2[k] then table.insert(ret, k) end
end
for k, _v in pairs(m2) do
  if not m1[k] then table.insert(ret, k) end
end
table.sort(ret)
print(#ret)
print(table.concat(ret, " "))